Here's how it works: 1) There are no seats, just to let you know
2) The stage is set up in a way so that there is a catwalk that goes around it, this is called the ellipse. Inside that catwalk, is what is known as the pit. The rail for the pit would be the front row, right in front of the stage. 3) Outside of the ellipse is the rest of the GA area, most of us, I think, refer to the front row of the pit as outer rail.
If you want my advice, the pit is kind of a hectic place, and you get a far better overall view of all the stage has to offer, plus the show itself from the outer rail. This stage is kind of lifted higher off the ground than in the past, and as a result, I hear it's a bit of a pain to look up at it from the front row of the pit. But, in general, I'm kind of biased against the pit because I hated the one experience I had in there.
Hope that helps! Any other questions, feel free to ask. And yes, hope to see you in MPLS